The boy, a seventh-grade student at the school, was being evaluated Sunday night at a hospital after investigators tracked him down and served a search warrant Saturday at his family home.

Eleven guns were found there under lock and key and the boy didn’t have access to them, the San Diego County Sheriff’s Department said.

In the email, the boy listed one of his teachers by name and 23 unidentified classmates as his targets.

He also wrote about several types of firearms and said he had 3,000 rounds of ammunition.

The threat came two months after a man killed 20 students and six adults in a mass shooting at Sandy Hook Elementary School in Newtown, Conn. That event sparked a national debate over gun control with President Barack Obama proposing a ban on assault weapons, reducing the number of rounds a magazine can hold and requiring stricter background checks of gun purchasers.

John Collins, superintendent of the Poway Unified School District, called such a tragedy “my worst nightmare.” He praised law enforcement for acting quickly to prevent it in Poway.

“Obviously this situation is both saddening and disturbing,” Collins said Sunday. “However, it is critical that all touched by this threat understand that the system worked. An anonymous threat was made. He was identified and with multiple agencies working together, the threat was averted.”

The boy sent the email to a school administrator on Friday evening, authorities said. In it, he identified a specific teacher as a target and “at least 23 children” and made references to several firearms, including a .38-caliber Smith & Wesson Special Revolver and an M-16 rifle.

He also gave locations on campus for the shooting and wrote that it would take place during second period, or about 9:30 a.m. Monday.

The Sheriff’s Department was notified of the threat about 8 a.m. Saturday, prompting them to call in a Computer and Technology Crime High-Tech Response Team, a task force consisting of federal, state and local agencies that investigate technology-related crimes. Investigators were aided by an Internet service provider in tracking the source of the email.

Sheriff’s Capt. Bill Donahue said the student was identified and authorities were at his family’s Poway home with a search warrant by 5:30 p.m. Saturday.

The boy’s father owned several guns — all of them locked up and not accessible to the teenager — including five rifles, three shotguns and three handguns, all of which were confiscated, officials said.

Donahue said the boy’s parents were shocked and cooperated fully. There was no evidence that anyone else was involved in the threat. Donahue also had a warning for students considering making similar threats.

“Don’t ruin your life or throw it away over doing something stupid like sending an email threat or any type of threat at school,” he said.